FEATURE Robotics
ROBOTS IN THE DRIVING SEAT
Keith Johnston, Sales Manager at RARUK Automation, states that with modern technologies such as collaborative robots and specialised screwdriving kits, it is possible to bring robotics to a host of processes involving high-mix, low-volume operations, without the high costs of conventional screwdriving automation
O
f all the repetitive tasks found in the world of engineering assembly, screwdriving is arguably the most mundane.
Alongside boredom, this task is also extremely laborious and carries a risk of musculoskeletal disorders such as carpal tunnel syndrome. Motivating employees to perform manual screwdriving is therefore extremely challenging. With these challenges in mind, a
growing number of companies are turning to robotic screwdriving, which today is a far cry from the complex process of a few years ago. However, not only do conventional screwdriving automation systems require heavy investment and a sizeable amount of shop-fl oor space, but most are inherently infl exible. Changing jobs requires considerable reconfi guration, often involving new tooling and new programs. Deploying and commissioning these types of systems is also prohibitively long, typically 8-17 weeks.
Cobots to the rescue The answer, as more and more are discovering, is to let a cobot take the strain. With the right application kit, programming a screwdriving task takes a matter of minutes, rather than days, and requires no special skills. There are many further benefi ts, too, not least improved consistency and enhanced fl exibility – users can easily reassign cobots to other tasks as needed. Quick deployment (days not months) is an additional advantage, alongside enhanced reliability, rapid return-on- investment (typically a few months), consistent accuracy (fractions of a millimetre) and small footprint (set up on a standard table).
32 March 2022 | Automation
Many of these benefi ts also apply in comparison with manual screwdriving, with the addition of eliminating inconsistent productivity and reducing operator injuries and sick days. Of course, optimising the integration of a robotic screwdriving cell will always benefi t from the input of an experienced automation specialist. In the fi rst instance, certain factors will make life easier, like simple part alignment and the use of clamps or a jig to hold the assembly. Once these elements are in place, it is then possible to begin designing the screwdriving cell, setting out the positions of the cobot/screwdriver, fi xture/ assembly, screw presenting device, light curtain and HMI. In most situations, the cobot will sit between two workbenches, so the overall cell needs to be compact.
Screwdriving challenges With regard to screwdriving, part tolerance, screw characteristics and screwdriver precision are all variables that can create a faulty fastening operation. To mitigate these errors, it is advisable to build the robot program in such a way that it can generate a recovery sequence, or signal to an operator that it has encountered a problem. By way of example, if torque is reached too early due to a cross thread, the robot should be precise enough to recognise the fault and trigger an ‘if’ condition, since the required distance has not been reached. The screwdriver can then unscrew the fastener and discard it. Any new robotic screwdriving cell should also feature a design that facilitates easy job changeover. The good news is that the program, complete with robot
home position and diff erent sensor IDs, can all remain the same when switching to a new screw type. In terms of hardware, the bit and screw holder are probably the only things that require changing on the screwdriver side, while the screw feeder might require some minor adjustments. Once set up, product changeovers should be possible within fi ve minutes. The best way to get started is to use a suitable kit of system components, such as the newly-introduced Robotiq Screwdriving Kit (see below), available in the UK from RARUK Automation. It comprises all the hardware and software elements needed to convert a cobot into a highly-productive screwdriving cell, within days. Key to this is the Robotiq screwdriving universal robot cap that allows easy set-up and simple programming because it automates the force-sensing capabilities and communication between the screwdriver, screw feed and vacuum technology. Above all, no robotics experience is required.
CONTACT:
RARUK Automation
www.rarukautomation.com
automationmagazine.co.uk
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